Assam
Summary
- Eastern hoolock gibbons (Hoolock leuconedys) and Western hoolock gibbons (Hoolock hoolock) are present in Assam.
- The population sizes are unknown.
- The eastern hoolock gibbon population trend is decreasing.
- The site has a total size of 78,438 km².
- Key threats to gibbons are habitat encroachment and illegal logging.
- Conservation activities are not documented.
Site characteristics
The state of Assam is located in northeast India, comprising two global biodiversity hotspots: the Indo-Burma and the Himalayan (Mazumder 2014). The area is a flat plain that gradually slopes from north to south, with vegetation characterised by tropical wet evergreen forest (Mazmuder 2014). The region is a stronghold for 12 primate species: Bengal slow loris Nycticebus bengalensis, Rhesus macaque Macaca mulatta, Assamese macaque Macaca assamensis, pig-tailed macaque Macaca leonina, stump-tailed macaque Macaca arctoides, Tibetan macaque Macaca thibetana, white-cheeked macaque Macaca luecogenys, capped langur Trachypithecus pileatus, golden langur Trachypithecus geei, Phayre’s langur Trachypithecus phayrei, western hoolock gibbon Hoolock hoolock, and eastern hoolock gibbon Hoolock leuconedys (Chetry et al. 2021).
Table 1. Basic site information for Assam
| Area | 78,438 km² |
| Coordinates | 25.521581 N, 93.051847 E |
| Designation | Unclassified |
| Habitat types | Subtropical/tropical moist lowland forest |
Ape status
In 2009, Chetry et al. (2012) recorded 33 eastern hoolock gibbons in 10 groups based on direct sightings in the reserve forests of Hal logaon, Kukurmara, and Kundil Kalia (Chetry et al. 2021). In 2019, 17 individuals in seven groups in these three reserve forests were recorded, indicating a 48.5% population decline. The number of groups were also reduced from 26 (direct observations and call-count) in 2009 to 11 in 2019 (Chetry et al. 2021). In this time frame there was also a 18.75% increase in the proportion of adults to immatures, indicating reduced recruitment and population decline (Chetry et al. 2021).
Table 2. Ape population estimates in Assam
| Species | Year | Total number indiv. (95% CI) | Total number groups (95% CI) | Density [groups/km²] (95% CI) | Area | Method | Source | Comments | A.P.E.S. database ID |
|---|---|---|---|---|---|---|---|---|---|
| Hoolock leuconedys | 2019 | 17 | 7 | Sadiya subdivision, 789.95 km² | Line transects (Distance) | Chetry et al. 2019 | Survey effort 98 km. Average group size was 2.42 | ||
| Hoolock hoolock | 2017-2018 | Upper Brahmaputra Valley, 9851 km² | Unknown | Sarma et al. 2021 |
Threats
Habitat encroachment and selective illegal logging represent the most severe threats to gibbons and other wildlife in Assam (Chetry et al. 2021).
Table 3. Threats to apes in Assam
| Category | Specific threats | Threat level | Quantified severity | Description | Year of threat |
|---|---|---|---|---|---|
| 1. Residential & commercial development | 1.1 Housing & urban areas | High | Encroachment due to expansion of human settlements (Chetry et al. 2021). | Ongoing (2021) | |
| 2. Agriculture & aquaculture | 2.1 Annual & perennial non-timber crops | High | Encroachment due to expansion of land for agriculture (Chetry et al. 2021). Jhum cultivation (a slash-and-burn type of shifting cultivation) has devastated large forest covers through the creation of canopy gaps and depletion of food (Mazumder 2014). | Ongoing (2021) | |
| 2.3 Livestock farming & ranching | Present, but threat severity unknown | Livestock grazing (Chertry et al. 2021). | Ongoing (2021) | ||
| 3. Energy production & mining | Unknown | ||||
| 4. Transportation & service corridors | Unknown | ||||
| 5. Biological resource use | 5.1 Hunting & collecting terrestrial animals | Present, but threat severity unknown | In certain places in southern Assam poachers specifically hunt these primates for their skin, hides, bones, skull, etc. (Mazumder 2014). | Ongoing (2014) | |
| 5.2 Gathering terrestrial plants | Present, but threat severity unknown | Exploitation of non-timber forest products such as cane bamboo and ferns (Chetry et al. 2021). | Ongoing (2021) | ||
| 5.3 Logging & wood harvesting | High | Selective illegal logging of certain species, including Uriam Bischoffia javanica, Simalu Bombax ceiba, Halakh Termina lia myriocarpa, and Titasopa Michelia champaca is causing canopy loss and creating fragments within the existing habitats (Chetry et al. 2021). Exploitation for firewood has also been documented (Chertry et al. 2021). | Ongoing (2021) | ||
| 6. Human intrusion & disturbance | Unknown | ||||
| 7. Natural system modifications | Unknown | ||||
| 8. Invasive & other problematic species, genes, diseases | Unknown | ||||
| 9. Pollution | Unknown | ||||
| 10. Geological Events | Absent | ||||
| 11. Climate change & severe weather | Unknown | ||||
| 12. Other options | Absent |
Conservation activities
Table 4. Conservation activities in Assam
| Category | Specific activity | Description | Year of activity |
|---|---|---|---|
| 1. Residential & commercial development | Not reported | ||
| 2. Agriculture & aquaculture | Not reported | ||
| 3. Energy production & mining | Not reported | ||
| 4. Transportation & service corridors | Not reported | ||
| 5. Biological resource use | Not reported | ||
| 6. Human intrusion & disturbance | Not reported | ||
| 7. Natural system modifications | Not reported | ||
| 8. Invasive & other problematic species, genes, diseases | Not reported | ||
| 9. Pollution | Not reported | ||
| 10. Education & Awareness | Not reported | ||
| 11. Habitat Protection | Not reported | ||
| 12. Species Management | Not reported | ||
| 13. Livelihood; Economic & Other Incentives | Not reported |
Challenges
Table 5. Challenges reported for Assam
| Challenge | Source |
|---|---|
| Not reported |
Research activities
Documented behaviours
Table 6. Ape behaviors reported for Assam
| Behavior | Source |
|---|---|
| Not reported |
External links
Relevant datasets
References
Chetry, D., Phukan, M., Chetry, S., Baruah, B., Deka, J. R., Das, A. K., ... & Bhattacharjee, P. C. (2021). The Eastern Hoolock Gibbon Hoolock leuconedys Population in Assam, India, is on the Verge of Extinction. Primate Conservation, (35).https://doi.org/10.13140/RG.2.2.26187.52005
Mazumder, M. K. (2014). Diversity, habitat preferences, and conservation of the primates of southern Assam, India: The story of a primate paradise. Journal of Asia-Pacific Biodiversity, 7(4), 347-354.https://doi.org/10.1016/j.japb.2014.10.001
Sarma, K., Saikia, M. K., Sarania, B., Basumatary, H., Baruah, S. S., Saikia, B. P., ... & Saikia, P. K. (2021). Habitat monitoring and conservation prioritization of Western Hoolock Gibbon in upper Brahmaputra Valley, Assam, India. Scientific reports, 11(1), 1-11. https://doi.org/10.1038/s41598-021-94844-8
Page completed by: A.P.E.S. Wiki team Date: 21/01/2022